JP4668432B2 - Electronic device mounting substrate, base plate integrated ceramic circuit substrate, and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device mounting substrate in which a base material made of a metal-metal, metal-carbon, or metal-ceramic composite, and a high thermal conductive ceramic substrate, including a metal mainly composed of copper, are integrally formed. Alternatively, the present invention relates to a base plate integrated ceramic circuit board and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, in the field of industrial equipment, the development of power modules used for inverters for electric motors has been progressing. Conventionally, high thermal conductive ceramic circuit boards equipped with silicon chips have been soldered to copper bases. Those having a structure have been used. However, since cracks occur in the ceramic substrate and the solder layer depending on the use conditions, various improvements have been made to improve the reliability by preventing these cracks.
[0003]
For example, an Al (aluminum) -SiC (silicon carbide) composite is used as a base material, and an AlN (aluminum nitride) substrate with an Al circuit (hereinafter referred to as an Al-SiC composite / aluminum nitride substrate with an Al circuit) is soldered. Although the attached structure maintains practical characteristics even after 3000 thermal cycles, it has much higher reliability than the conventionally known Cu (copper) base / aluminum nitride substrate with a copper circuit. Compared to the above, since the thermal resistance is large, it is necessary to increase the chip size, and since the Al-SiC composite is expensive, the module cost is increased, and thus it has not been widely spread.
[0004]
It has also been proposed to integrate the Al-SiC composite with a ceramic substrate or a ceramic circuit board when manufacturing the Al-SiC composite. In this case, since there is no solder layer between the composite and the substrate, there is no concern that cracks will occur in the solder in that part, and there are advantages such as improved reliability and reduced thermal resistance. Has a thermal conductivity of no more than 200 W / mK, and further reduction in thermal resistance is required to increase the capacity and size of the power module.
[0005]
[Problems to be solved by the invention]
The present inventor has studied variously in view of the above circumstances, and the base plate and the ceramic circuit board can be integrated only through a process of manufacturing a metal-metal, metal-carbon, or metal-ceramic composite. The present inventors have found that an electronic component mounting substrate having thermal cycle resistance and low thermal resistance can be provided, and the present invention has been achieved. That is, an object of the present invention is to provide an electronic mounting substrate and a base plate integrated ceramic circuit substrate capable of supplying a power module having low thermal resistance, excellent thermal cycle resistance, and thus excellent long-term reliability with high reproducibility. There is.
[0006]
[Means for Solving the Problems]
The present invention includes a base plate that has or does not have a recess on one main surface, a ceramic substrate that is disposed on the main surface of the base plate and is smaller than the base plate, the base plate, and the ceramic substrate. A surface of the metal layer that does not contact the base plate and the ceramic substrate is planar, and the base plate is metal-metal, metal- It is carbon or a metal-ceramic composite, wherein the metal in the composite and the metal layer are mainly composed of copper, and the purity of the metal layer is higher than the purity of the metal in the composite. This is an electronic device mounting board.
[0007]
Moreover, this invention is said board | substrate for electronic device mounting characterized by having a plurality of ceramic substrates. According to another aspect of the present invention, there is provided a base plate-integrated ceramic circuit board formed by forming a circuit from a metal layer of an electronic device mounting board.
[0008]
The present invention also provides a base plate-integrated ceramic circuit board comprising a ceramic circuit board having a circuit on one main surface and a base plate provided in contact with the main surface on which the circuit of the ceramic circuit board is not provided. The base plate is made of a metal-metal composite, a metal-carbon composite, or a metal-ceramic composite, and the surface of the circuit and the ceramic substrate of the base plate are mounted on the surface on which the ceramic substrate is not provided. And a base plate integrated type wherein the metal contained in the circuit and the base plate is mainly composed of copper and the purity of the metal layer is higher than the purity of the metal in the composite It is a ceramic circuit board.
[0009]
In the present invention, the base plate is composed of a porous molded body mainly composed of one or more selected from carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten, and molybdenum. A base plate-integrated ceramic circuit board characterized by being a composite body impregnated with a metal to be used.
[0010]
Further, the present invention is a porous material mainly comprising at least one selected from carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum, and having or not having a recess on one main surface. A ceramic substrate is disposed on the main surface of the molded body, and a metal plate mainly composed of copper is disposed so as to cover at least a part of the porous molded body and the ceramic substrate, thereby forming a laminate. The laminate is placed in a container, a metal mainly composed of copper is cast, and the voids of the porous molded body are impregnated with the metal mainly composed of copper, and the porous molded body and the metal plate In addition, the present invention is a method for manufacturing a substrate for mounting an electronic device, wherein a ceramic substrate is integrated.
[0011]
Further, the present invention is a porous material mainly comprising at least one selected from carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum, and having or not having a recess on one main surface. A ceramic substrate is disposed on the main surface of the molded body, and a metal plate is further disposed so as to cover at least a part of the porous molded body and the ceramic substrate, thereby forming a laminated body. The metal is composed mainly of copper, and the porous molded body is impregnated with the metal mainly composed of copper, and the porous molded body, the metal plate and the ceramic substrate are integrated. And then forming a circuit from the metal layer formed on the surface opposite to the base plate of the ceramic substrate or the metal plate. It is a manufacturing method.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The electronic device mounting substrate of the present invention is characterized in that it can be manufactured by integrating the base plate and the ceramic substrate in accordance with the manufacturing method of the metal-metal, metal-carbon, or metal-ceramic composite used as the base plate. .
[0013]
The methods for producing metal-metal, metal-carbon, or metal-ceramic composites are roughly classified into two types: an impregnation method and a powder metallurgy method. Among these, the powder metallurgy method is low in manufacturing cost but is not sufficient in terms of the characteristics of the obtained composite, and the impregnation method is advantageous in terms of the characteristics of the resulting composite although the manufacturing cost is high. There are various impregnation methods, and there are a method performed at normal pressure and a method performed under high pressure (high pressure casting method). What is performed under high pressure includes a molten metal forging method and a die casting method. Both the molten metal forging method and the die casting method are porous with a certain degree of strength in a final shape, or a mold that is almost similar to the final shape, or a mold (or room) composed of a frame and a plate. This is a method in which a body (preform) is loaded and this is impregnated with copper (Cu) or a molten Cu alloy at a high pressure to obtain a composite.
[0014]
In the present invention, any method may be used, but a type performed under high pressure is preferable in view of characteristics (coexistence of high thermal conductivity and low thermal expansion coefficient and heat cycle resistance). If the ceramic plate and the circuit board are joined or the metal layer for the circuit is formed during the impregnation operation, it is possible to obtain a circuit board precursor obtained by joining the ceramic substrate at a lower cost.
[0015]
When the preform is impregnated with the molten Cu at the same time as the integration with the substrate, conventionally, (1) the ceramic circuit board is placed in contact with the preform, and the preform is joined with the ceramic while the preform is impregnated with the molten Cu. Performing (2) A method is known in which a ceramic substrate is placed in contact with a preform and the preform is impregnated with a molten Cu and bonding to the ceramic substrate and formation of a metal layer for a circuit are performed simultaneously.
[0016]
The method (1) is disadvantageous in terms of cost because it requires a step of joining a circuit metal to a ceramic substrate in advance or forming a circuit after providing a metal layer on the ceramic substrate. In the method (2), since a copper alloy having a low melting point is often used as the impregnated metal, the thermal conductivity and electric conductivity of the impregnated metal layer used in the circuit are lowered, which is disadvantageous in characteristics. Further, since the alloy is harder than pure copper, the stress generated in the bonded ceramic substrate such as AlN is increased, which may cause problems such as substrate cracking. When pure copper is used for the impregnated metal, the adhesion with ceramics is inferior, and the heat cycle resistance may be lowered.
[0017]
As a result of intensive studies, the inventors of the present invention have the following configuration, which can be manufactured relatively easily, with high accuracy, and as a result, at low cost, from a metal-metal or metal-ceramic composite. It was found that an integrated ceramic circuit board with a base plate can be obtained.
[0018]
That is, a ceramic substrate is placed in contact with the preform, and a Cu plate is placed in contact with the preform, followed by preheating and impregnation with molten Cu at a high pressure to obtain a substrate for mounting an electronic component. By forming a circuit from a plate by a conventionally known method such as etching, a base plate-integrated ceramic circuit board to which a circuit made of a Cu plate having a certain thickness is bonded can be obtained.
[0019]
When the preform is impregnated with Cu, preheating is generally performed so that the molten Cu is easily impregnated into the preform. However, in the present invention, a Cu plate is present during the preheating. Even if the Cu plate does not melt, it is based on the discovery that the Cu plate keeps the charged form even when the Cu alloy contacts the Cu plate.
[0020]
Surprisingly, it has been found that the base plate-integrated ceramic circuit board obtained in this way has extremely useful characteristics in practice. For example, the thermal expansion coefficient of a Cu-SiC composite plate is determined by the SiC volume percentage in the composite, and is generally about 6 to 9 ppm / K. Therefore, AlN (aluminum nitride) or Si _Three N _Four When a ceramic substrate having a low coefficient of thermal expansion such as (silicon nitride) is soldered or brazed, a large warp with the ceramic side convex is generated. This warp creates a gap between the base plate and the heat dissipating fin when screwing and fixing it to the heat dissipating fin or the like, thereby hindering heat transfer. For this reason, it has been necessary to give a warp in which the joint surface with the heat dissipating fins or the like is concave in advance to the base plate by some method. However, in the base plate integrated ceramic circuit board of the present invention, since the thermal expansion coefficient of Cu constituting the surface circuit is large, in the case of AlN, Si is substantially flat and has a smaller thermal expansion coefficient than that of AlN. _Three N _Four In this case, the circuit warps slightly, but the degree of the warp is such that it can be changed to a warp with the circuit side concave in the module assembling process. It exhibits favorable characteristics.
[0021]
Hereinafter, the example in the case of manufacturing a Cu-SiC composite body by the impregnation method under a high pressure is explained in full detail about this invention.
First, a method for producing a Cu—SiC composite will be described.
SiC powder is molded, calcined to obtain a preform, placed on a partition plate whose surface has been subjected to a mold release treatment, and then set in a frame-shaped mold that has been hollowed out so that the inner dimensions are the final shape. . After preheating the block, which has been fixed in layers, placed in a pressure-resistant container, in order to prevent the temperature of the block from dropping, pour molten Cu into the container as quickly as possible and pressurize the molten Cu. , Cu is impregnated into a preform placed in a frame-shaped mold.
[0022]
In the present invention, when the preform is set in the frame-shaped mold in the above steps, the same operation as that for obtaining the Al-SiC composite is further performed by merely arranging the ceramic substrate and the Cu plate. Thus, an electronic component mounting substrate in which the base plate and the ceramic circuit substrate are integrally bonded, or a base integrated ceramic is obtained.
[0023]
In the above-described operation, it is convenient that accurate positioning can be achieved if a recess having the same area as the ceramic substrate is provided on one main surface of the preform and the ceramic substrate is disposed there. In addition, it is preferable that the metal plate for a circuit is provided with the same outer dimension as the inner dimension of the frame, so that there will be no misalignment in subsequent handling, and positioning in the subsequent process becomes unnecessary.
[0024]
As is apparent from the above description, the porous silicon carbide preform to be used need not have any special restrictions, and any can be used. It is preferable to select what has. That is, among the characteristics of the Cu—SiC composite, particularly important characteristics are thermal conductivity and thermal expansion coefficient. The higher the silicon carbide (SiC) content in the composite, the smaller the thermal expansion coefficient, but the lower the thermal conductivity, practically, the relative density of porous silicon carbide is 30 to 70 vol%. Preferably it is in the range. Further, if the preform has a bending strength of 3 MPa or more, it is preferable that there is no fear of cracking during handling or impregnation.
[0025]
About the silicon carbide (SiC) powder which is the raw material of the said porous silicon carbide, it is preferable to perform particle size mixing. This is because the strength development is poor with only the coarse powder, and the thermal conductivity is lowered with only the fine powder. According to the study of the present inventor, for example, 40 to 80% by mass of silicon carbide coarse powder having a particle size of # 350 or more and 60 to 20% by mass of silicon carbide fine powder having a particle size of # 1000 or less are mixed. Use it.
[0026]
Carbon, ceramics, or metal powder or fiber is molded, subjected to degreasing and firing steps to become a preform, which is subjected to the impregnation operation. As described above, since it is advantageous in the process that the preform has a recess for positioning the ceramic substrate, the molding method is preferably a molding method using a mold such as injection molding, dry molding, or wet molding. . In addition, in the case of extrusion molding, it is not easy to provide a recess on the main surface, but it can be used in the same way because the problem of positioning can be reduced by means of stuffing the frame, such as making the recess into a groove shape, etc. Is possible.
[0027]
In order to develop the strength of the preform to 3 MPa or higher, it is preferable to perform baking in a non-oxidizing atmosphere or an oxidizing atmosphere and set the baking temperature to 850 ° C. or higher. In the case of a silicon carbide (SiC) preform, it is desirable to fire at a temperature not exceeding 1100 ° C. when firing in air so that SiC is not oxidized and its thermal conductivity is not lowered.
[0028]
The frame material for storing the preform has a gate for introducing the molten Cu into the mold (inside the room), and iron is effective. It is obtained by laser processing or punching press, and is provided after release treatment. For the mold release treatment, fine graphite powder is effective. The partition plate is preferably an iron or stainless steel plate. Applying fine graphite and / or BN (boron nitride) after treatment such as oxidation prevention is extremely effective for mold release. The thickness of the partition plate is selected according to the thickness and accuracy of the target product. If the thickness variation of the product is to be suppressed to 20 μm or less, the thickness may be reduced to about 0.3 mm if a plate of 3 mm or more and about 50 μm are allowed.
[0029]
As the ceramic substrate used in the present invention, AlN, Si _Three N _Four , Al ₂ O _Three General-purpose ceramics such as (alumina) are used, but for the purposes of the present invention, ceramics with high thermal conductivity are preferred, such as AlN and Si. _Three N _Four Nitride ceramics are preferred.
[0030]
The metal plate for circuit in the present invention may be any metal plate as long as it has a melting point higher than that of the impregnated metal constituting the base plate, but can form a circuit and heat. Those having high conductivity and high electrical conductivity are preferable, and any Cu plate having a purity of 98.5% by mass or more can be used. However, in order to achieve both higher reliability and excellent physical properties, the purity of the Cu plate is 99.5% or more, more preferably 99.9% or more of a high-purity Cu plate, particularly an oxygen-free copper plate. It is good. The thickness of the circuit material is generally about 0.2 to 0.5 mm, but 0.2 to 0.4 mm when the ceramic substrate is AlN, Si _Three N _Four In this case, 0.3 to 0.5 mm is preferable.
[0031]
The circuit metal plate can be used not only as a circuit material but also as a positioning material. For example, when a preform is molded by extrusion molding or the like, it is difficult to process the cavity for placing the ceramic substrate, so a circuit metal plate with a hollow hole for housing the ceramic substrate is placed in contact with the preform and positioned. A ceramic substrate is arranged as a jig, and a metal plate for a circuit is arranged thereon. In this case, in order to facilitate the penetration of the molten Cu, it is preferable to provide a through-hole in the positioning metal plate in addition to the substrate position. Furthermore, you may cut and use an unnecessary part for the metal plate for circuits.
[0032]
A preform, a ceramic substrate, and a circuit metal plate, which are housed in a room separated by a frame and a partition plate, are stacked and fixed to form a block for impregnation, and the block is put in a preheating furnace and preheated. The preheating temperature needs to be an appropriate temperature depending on the metal to be impregnated, and the upper limit temperature needs to be lower than the melting point of the circuit metal plate. According to an experimental study by the present inventor, the preform is a porous silicon carbide sintered body, the impregnated metal is a Cu alloy containing 3% by mass of Si and 0.7% by mass of Mg. When oxygen-free copper is used as the metal plate, 1000 to 1070 ° C. is a preferable range. If it is 1000 ° C. or lower, impregnation may be poor, and if it is 1070 ° C. or higher, the oxygen-free copper plate may be melted. Moreover, in order to prevent a copper plate from oxidizing during preheating, it is necessary to heat by inert atmosphere and reducing atmosphere as needed.
[0033]
The preheated impregnation block is placed in a pressure resistant container, and the molten Cu alloy is pushed into the pressure resistant container and pressurized to impregnate the preform with the molten alloy, and at the same time the ceramic substrate and circuit metal Complete the bonding with the board. When a high-purity Cu plate having a purity of 99.5% or more is used for the metal plate for a circuit and the Cu alloy to be impregnated is a combination of the above compositions, there is no problem if the hot water temperature of the supplied Cu alloy is 1100 to 1200 ° C. When the temperature is lower than the above range, impregnation failure may occur. When the temperature is higher, melting of the high purity Cu plate may occur. In order to prevent oxidation of the molten Cu alloy, the molten metal is preferably maintained in an inert atmosphere or a reducing atmosphere.
[0034]
The metal to be impregnated may have a lower melting point than the circuit metal plate, and a Cu alloy is selected when the circuit metal plate is an oxygen-free copper plate. The reason why the Cu alloy is preferably selected is that it melts below the melting point of the oxygen-free copper plate, shows a strong bond with the preform or ceramic substrate, and fuses with the oxygen-free copper plate on the surface and does not produce a brittle alloy. This is because the object of the present invention can be sufficiently achieved.
[0035]
As the Cu alloy, a Cu alloy containing a component whose melting point decreases when added in a small amount is preferable. However, although a small amount of P (phosphorus) lowers the melting point, it is not preferable because the thermal conductivity is greatly lowered. Among various Cu alloys, Cu—Si based alloys are preferable. This is because Si lowers the melting point in a smaller amount than other additive elements and reduces the decrease in thermal conductivity. The amount is 0.5 to 10% by mass, preferably 1.0 to 5.0% by mass. Furthermore, the Cu—Si-based alloy to which a trace amount of a group 2a element such as Mg or Ca, a group 3a element such as Y, or a group 4a element such as Ti or Zr can be bonded to a stronger ceramic. Is more preferable. A sufficient effect is obtained when the amount of the additive element is 1% by mass or less.
[0036]
After completion of the impregnation operation, after cooling and solidifying, the outer Cu alloy is cut off, the contents are disassembled, and the release material attached to the surface is removed by buffing, sandblasting, etc., so that one main surface of the Cu-SiC composite A substrate on which a ceramic substrate is mounted, and a circuit metal plate is bonded to at least a part of both surfaces thereof is obtained. The substrate is a base plate on which various electronic devices such as semiconductor elements can be mounted only by forming a circuit from the circuit metal plate by etching or the like, and by performing processing or plating as necessary. An integrated ceramic circuit board can be easily provided.
[0037]
Further, in the operation of obtaining the substrate, it is possible to obtain a substrate in which a plurality of ceramic circuit substrates are mounted on one base plate only by arranging a plurality of ceramic substrates on one main surface of the preform in advance. This substrate has an advantage that it can easily provide a module having a structure in which a plurality of ceramic circuit boards are mounted on one base plate, and contributes to higher density of electronic components. In any of the above cases, in the base plate integrated ceramic circuit board of the present invention, the surface of the circuit and the surface of the metal layer on the surface of the base plate are formed on the same plane.
[0038]
Although part or all of the metal layer on the surface of the base plate can be removed in the course of etching or the like, according to the study of the present inventor, it is usually used at a low voltage of 3 mm or more from the end of the circuit. In this case, it is sufficient to etch a region of 1 mm or more, and removal of a region further away only increases the etching amount and does not contribute to improvement of circuit characteristics.
[0039]
As described above, the case where the Cu-SiC composite material is used for the base plate has been described in detail. Instead of silicon carbide powder, powder or fiber of carbon, alumina, aluminum nitride, silicon nitride, tungsten, molybdenum, copper oxide, or the like is used. Even if it uses, the board | substrate of this invention can be obtained like the case where the said SiC powder is used. When metal powder is used, a preform can be obtained by cold isotropic press (CIP) molding without going through a firing step, and it is important to maintain a non-oxidizing atmosphere or reducing atmosphere in the impregnation step. The impregnated metal is preferably a metal to which a small amount of Group 4a element is added. When fibers are used, preforms can be made by casting or the like if they are short fibers, and if they are long fibers, they can be woven into a cloth shape to form a preform.
[0040]
In addition to the method of impregnating under high pressure using the preform described in detail, the metal powder and metal powder, metal powder and carbon powder, or metal powder and ceramic powder constituting the composite body as the base plate are mixed, It is also possible to manufacture a substrate in which the substrate and the base plate are integrated by heating it above the melting point of the matrix metal and injecting it into a molding die in which a circuit metal plate and a ceramic plate are arranged. . In the portion other than the matrix metal, a fibrous substance can be used in addition to the powder.
[0041]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to this.
[0042]
[Example 1]
70 g of silicon carbide powder A (manufactured by Taiyo Random Company: NG-220, average particle size: 60 μm), 30 g of silicon carbide powder B (manufactured by Yakushima Electric Works: GC-1000F, average particle size: 10 μm), and silica sol (Nissan Chemical) 10 g (Snowtex Co., Ltd.) was weighed and mixed for 30 minutes with a stirring mixer, and then a flat plate with dimensions of 110 mm × 90 mm × 4.6 mm having a cavity of 50 mm × 50 mm × 0.6 mm on one side of the central part. Molded into. At this time, the pressure during molding was set to 10 MPa.
[0043]
The obtained molded body was fired in the atmosphere at a temperature of 950 ° C. for 2 hours to obtain a porous silicon carbide sintered body having a relative density of 65 volume%.
[0044]
Next, the obtained porous silicon carbide sintered body was placed on a 0.7 mm-thick partition plate coated with a release agent, which was also coated with the release agent (material: Carbon steel), and an aluminum nitride substrate having a characteristic of 170 W / mK of 50 × 50 × 0.6 mm is inserted into the cavity of the porous silicon carbide sintered body, and then the porous silicon carbide sintered body An oxygen-free copper plate having a thickness of 0.3 mm, which is equal to the outer dimensions of the plate, was placed thereon. In this state, the height of the contents and the frame height are substantially equal. This was overlaid with a partition plate coated with a release agent (same as the above-mentioned partition plate and the same size as the outer dimensions of the mold), and a 6 mm thick iron plate was placed on both ends to form one block.
[0045]
Next, the block was preheated to a temperature of 1050 ° C. in an electric furnace, placed in a preheated mold, and then heated to a temperature of 1100 ° C., 2% by mass of Si and 0.1% of Ti. A molten Cu alloy containing 5% by mass was poured and pressurized at a pressure of 100 MPa for 10 minutes to impregnate the porous silicon carbide sintered body with the Cu alloy. The obtained metal mass containing the composite was cooled to room temperature, and then cut with a band saw to release the base plate integrated ceramic substrate from the mold. A cross-sectional view of this state is shown in FIG.
[0046]
In order to remove the mold release agent on the surface of the base plate integrated ceramic substrate, it was passed through a buffing machine equipped with a # 220 baffle. After removing the release agent, an etching resist having a desired pattern was printed on the surface of the copper plate, the back and side surfaces were solid, and unnecessary portions were dissolved with a ferric chloride solution. Furthermore, after processing holes for attaching the radiation fins, plating was performed to obtain a base plate integrated ceramic circuit board. The plating was made of two layers of electroless Ni—P; 5 μm and electroless Ni—B; 2 μm. A cross-sectional view of this state is shown in FIG. Further, the warping amount at this time was approximately 0 μm.
[0047]
Next, a 12 mm square and 0.4 mm thick silicon chip was soldered to the circuit pattern of the base plate integrated ceramic circuit board, and a thermal cycle test was performed. The conditions of the cold cycle test were -40 ° C; 30 minutes, in air; 10 minutes, 125 ° C; 30 minutes, and 10 minutes in air as one cycle. After 1000 cycles, the presence or absence of cracks in the solder part under the silicon chip, cracks in the substrate itself, circuit peeling, etc. were observed in detail, but no abnormality was found.
[0048]
[Example 2]
70 g of silicon carbide powder A (manufactured by Taiyo Random Company: NG-220, average particle size: 60 μm), 30 g of silicon carbide powder B (manufactured by Yakushima Electric Works: GC-1000F, average particle size: 10 μm), and silica sol (Nissan Chemical) After weighing 10 g with a stirrer and mixer for 30 minutes, it was molded into a shape of 110 mm × 90 mm × 4 mm at a pressure of 10 MPa.
[0049]
The obtained molded body was heated in the atmosphere at a temperature of 950 ° C. for 2 hours to obtain a porous silicon carbide sintered body having a relative density of 65 volume%. Next, the porous silicon carbide sintered body was placed on a 0.7 mm thick partition plate coated with a release agent, which was also coated with the release agent (material: carbon). Steel), an oxygen-free copper plate having a thickness of 0.3 mm and having a 50 × 50 window at the center and having an outer dimension substantially equal to the outer dimension of the porous silicon carbide sintered body. Next, after inserting a silicon nitride substrate having a characteristic of 100 W / mK of 50 × 50 × 0.4 mm into the window portion of the oxygen-free copper plate, the outer dimension of the porous silicon carbide sintered body is approximately equal to the outer dimension. A 4 mm thick oxygen-free copper plate was placed on top of this. In this state, the height of the contents and the frame height are substantially equal. A cross-sectional view in this state is shown in FIG. Further, a partition plate coated with a release agent (same as the above-described partition plate and the size is the same as the outer size of the mold) was overlapped, and an iron plate having a thickness of 6 mm was disposed on both sides, and then one block was formed.
[0050]
Subsequent operations were the same as those in Example 1 to obtain a base plate integrated ceramic circuit board. A cross-sectional view in this state is shown in FIG. The surface is Ni-P plated 5 [mu] m and Ni-B plated 2 [mu] m. The amount of warping at this time was about 100 μm with the concave circuit surface.
[0051]
A silicon chip having a 12 mm square and a thickness of 0.4 mm was soldered to the circuit pattern of the base plate integrated circuit board, and the cooling cycle test shown in Example 1 was performed. After 1000 cycles, The presence or absence of cracks in the solder portion, substrate cracking, circuit peeling, etc. were observed in detail, but no abnormality was observed.
[0052]
[Comparative example]
70 g of silicon carbide powder A (manufactured by Taiyo Random Company: NG-220, average particle size: 60 μm), 30 g of silicon carbide powder B (manufactured by Yakushima Electric Works: GC-1000F, average particle size: 10 μm), and silica sol (Nissan Chemical) 10 g in a flat plate with a cavity of 110 mm x 90 mm x 4.6 mm and a cavity of 50 mm x 50 mm x 0.6 mm on one side of the center after weighing 10 g with a stirring mixer. Molded at a pressure of
[0053]
The obtained molded body was heated in the atmosphere at a temperature of 950 ° C. for 2 hours to obtain a porous silicon carbide sintered body. The relative density of the obtained porous silicon carbide sintered body was 65% by volume.
[0054]
Next, the obtained porous silicon carbide sintered body was placed on a 0.7 mm-thick partition plate coated with a release agent, which was also coated with the release agent (material: The carbon nitride steel plate was inserted into the cavity portion of the porous body, and a 170 W / mK aluminum nitride substrate of 50 × 50 × 0.6 mm was inserted. In this state, the frame height was about 0.4 mm higher than the content height. A partition plate coated with a release agent (same as the above-mentioned partition plate and the same size as the outer dimensions of the formwork) was overlapped thereon, and an iron plate having a thickness of 6 mm was disposed on both sides, and then one block was formed. At this time, care was taken so that the aluminum nitride substrate placed in the cavity would not be detached from the cavity so that the substrate side was always located at the top.
[0055]
Next, the block is preheated to a temperature of 1050 ° C. in an electric furnace and placed in a preheated mold, taking care not to detach the aluminum nitride substrate from the cavity, and then the temperature of 1100 ° C. A molten Cu alloy containing 2% by mass of Si and 0.5% by mass of Ti, which was heated, was pushed in and pressurized at a pressure of 100 MPa for 10 minutes to impregnate the porous silicon carbide sintered body with the Cu alloy. . The obtained metal lump containing the composite was cooled to room temperature and then cut with a band saw to release the base plate-integrated ceramic substrate from the mold.
[0056]
Thereafter, the same operation as in Example 1 was performed to obtain a base plate integrated ceramic circuit board. A cross-sectional view in this state is shown in FIG. The amount of warpage was approximately 50 μm with the circuit side being convex.
[0057]
A 12 mm square and 0.4 mm thick silicon chip was soldered to the circuit pattern of the base plate integrated ceramic circuit board, and the thermal cycle test shown in Example 1 was performed. There were through cracks.
[0058]
【The invention's effect】
The base plate integrated ceramic circuit board of the present invention can be easily manufactured with a high yield and is excellent in mass productivity. And since it has excellent heat dissipation and has a warp amount that is practically acceptable, a power module manufactured using this can be downsized, has high reliability, Even in connection, it exhibits excellent industrially useful effects such as no increase in thermal resistance. Furthermore, the substrate for mounting electronic equipment according to the present invention can be easily provided with the base plate-integrated ceramic circuit board that can be mounted on electronic equipment by etching a part of the metal layer on the surface, which is industrially useful. is there.
[Brief description of the drawings]
FIG. 1 is a plan view of a frame material used for an impregnation operation in Examples and Comparative Examples of the present invention.
FIG. 2 is a cross-sectional view for explaining the structure of a base plate integrated ceramic substrate (electronic device mounting substrate) in Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional view for explaining the structure of a base plate integrated ceramic circuit board according to Embodiment 1 of the present invention.
FIG. 4 is a view for explaining the arrangement of members immediately before impregnation in Example 2 of the present invention.
FIG. 5 is a cross-sectional view for explaining the structure of a base plate integrated ceramic circuit board according to a second embodiment of the present invention.
FIG. 6 is a cross-sectional view for explaining the structure of a base plate integrated ceramic circuit board according to a comparative example.
[Explanation of symbols]
1: Frame material
2: Molten metal introduction part (pouring gate)
3: Preform storage section
4: Metal layer (copper plate)
5: Ceramic substrate
6: Metal-ceramic composite (Cu-SiC composite)
7: Circuit (copper plate)
8: Copper plate
9: Copper plate
10: Porous inorganic sintered body (Preform: Porous silicon carbide sintered body)
11: Metal for impregnation (Cu alloy)
12: Circuit (Cu alloy)

Claims (7)

A base plate having or not having a recess on one main surface, a ceramic substrate disposed on the main surface of the base plate and smaller than the base plate, and at least a part of the base plate and the ceramic substrate A surface of the metal layer that does not contact the base plate and the ceramic substrate is planar, and the base plate is a metal-metal composite , a metal-carbon composite. body or metal, - a ceramic composite, and wherein the metal in the complex and said metal layer is composed mainly of copper, and the purity of the metal layer is higher than the purity of the metal in said complex Electronic equipment mounting board. The electronic device mounting substrate according to claim 1, wherein there are a plurality of ceramic substrates. A base plate-integrated ceramic circuit board, wherein a circuit is formed from a metal layer of the electronic device mounting board according to claim 1. A ceramic circuit board having a circuit on one main surface, a base plate provided in contact with a main surface of the ceramic circuit board not provided with a circuit, and at least a part of the base plate and the ceramic circuit board together A base plate-integrated ceramic circuit board comprising a metal layer provided so as to cover the base plate, the base plate comprising a metal-metal composite, a metal-carbon composite, or a metal-ceramic composite, in the main surface of the ceramic substrate is mounted, said circuit surface and said it is the same height of the front surface of the ceramic substrate provided with no portion of the metal layer, yet, the metal contained in the circuit and the base plate is a copper A base plate-integrated ceramic circuit board characterized by comprising a main component and the purity of the metal layer being higher than the purity of the metal in the composite. A base plate is formed by impregnating a porous molded body mainly composed of one or more kinds selected from carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum with a metal mainly composed of copper. 5. The base plate-integrated ceramic circuit board according to claim 4, wherein the composite circuit board is a composite body. The main surface of the porous molded body having one or more kinds selected from carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum as a main component, and having or not having a concave portion on one main surface. A ceramic substrate is disposed on the substrate, and a metal plate mainly composed of copper is disposed so as to cover at least a part of the porous molded body and the ceramic substrate. The metal plate is made of a copper-based metal having a purity equal to or lower than that of the copper, and the voids of the porous molded body are impregnated with the metal containing the copper-based component, and porous. A method for producing a substrate for mounting electronic equipment, comprising: integrating a molded body, a metal plate, and a ceramic substrate. The main surface of the porous molded body having one or more kinds selected from carbon, silicon carbide, copper oxide, alumina, aluminum nitride, silicon nitride, tungsten and molybdenum as a main component, and having or not having a concave portion on one main surface. A ceramic substrate is disposed thereon, and further a metal plate or metal layer mainly composed of copper is disposed so as to cover at least a part of the porous molded body and the ceramic substrate, thereby forming a laminated body. Is placed in a container, a metal mainly composed of copper lower than the purity of the copper constituting the metal plate or metal layer is cast, and the metal mainly composed of copper is formed in the voids of the porous molded body. with impregnating a porous molded body, a metal plate and the ceramic substrate are integrated, the base plate integral ceramic times, characterized in that subsequently the metal plate or the metal layer from the circuit formation Method of manufacturing a substrate.

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